One thing after another

[BenBaron]

So, Ive got my SVA on Monday, and after going home last night and having a play, I find that my battery is totally dead, this doesnt bode well Im thinking, its one of the Red top batterys as well so its not a case of going out and getting a new one for cheap becasue its got different battery ends and the clamp is a bespoke shape.

So tried it after charging all night and its ok and managed to fire the engine up so thats ok (phew) but Im assuming I must have a drain somewhere on the car, but where/how do I find/check that? Im pretty sure I didnt leave the lights on all night but what else could have killed it so much?

Ben

ps I dont leave the keys in so the ignition was definatly off

[BenBaron]

could it be something to do with my alternator as I was messing about with it, and the battery has been fine for months?

[craggle]

Have you got a multimeter?

If so set it to measure amps and connect it inline with the battery and the battery lead. With everything off it should read zero amps (unless you have a radio in which case it will read a few milliamps)
If you get a reading try pulling the fusses out one at a time and see if one makes a difference. If the fuses make no change try disconecting the leads to the alternator.

Dont try turning anything on with the ammeter connected unless it is designed to go to a high amperage. My one is only rated to 10amps max.

Craig.

[Cobra289]

Hi Ben,

I think that you are running in interesting electrical problems.
I go for general earth problems, if the license plate fails, it doesn’t mean that the earth there is the problem, it can be a general earth in your wiring, and due to that other systems can also have funny behavior too.

I would advice to go first and check the alternator, provide at the alternator body a good earth and not via possible support brackets.

Engine, check and double check the earth, the best place are the heads, why because you will be at a suitable area and less possible insulators to the distributor.

Dash earth or earths, here there are a lot of possibilities for problems, like painted surfaces, threaded bolt connections are the best, on top of that use of “silicone paste”. Not the solid compound but the dielectric paste will solve for the length of years for a good connection and will protect the blank steel or the prone to rust connectors.

If you turn your indicator light and you see that the heads light goes on or other funny behaviors you can say for 100% that is an earth problem and the positive electricity has found a way to connect to earth via the positive wire.

Craig has mentioned a good way how to find a possible drain; I would advice to follow that practice.
If that doesn’t help than is time to see a doctor.

I hope that this help you.
Regards,
Cobra289

[AKBandit]

Hi Ben,
Just going back to the problems you were having with your alternator and a bit of guess work. If the two wires connecting to your alternator were the wrong way round, then I would guess it is possible you are discharging through the alternator. If this is the case and you do see current being drawn from the battery, pulling the fuses may not stop the discharge. If this is the case disconnect the two wires and see if that stops the discharge.
Mark

[Andy302]

I dont mean to be the prophet of doom but how long was your battery "flat"? If it was down below 11v for more than a couple of days then I would not be relying on it to have such a long life as before.

Im not sure about the red top batteries as to what technology they use byut if they are lead acid then sulphation will have started. If this is not removed by a recovery charge, nominally at around 16v for a short time, then the capacity Ah and CCA will be reduced as the sulphation reduces the active area of the plates. If keft for too long the sulphation will grow to such an extent that the plates may well become damaged and thats the end of your battery.

Sorry!

[BenBaron]

Hi Guys,

excellent info, will try and see what happens today.

The battery was flat as a pancake but only for a few hours, I got it back on charge soon as I found it, but it took a good 36 hrs to charge it back to full welly. Seems fine now, turns the engine over like a beast. I will check on the discharge theory through my alternator though.

thanks guys

Ben

[craggle]

The Optima red top batteries are an Absobed glass mat technology battery.

I use Odyssey batteries that use the same tecnology. They are basically lead plates that are tightly assembled with glass fibre mat between the plates. The glass fibre is then soaked in acid gell.
Because of this tight packing and the gell soaked mat, No gassing can occur and distortion of the lead plates can not happen.
The odyssey batteries are sold and shipped as drycell batteries as they are not vented and will not leak if punctured. They are also far more tollerant than a lead acid battery to being dicharged and re-charged. Odyssey quote 400 charge/discharge cycles to 100% depth of discharge.

http://www.odysseybatteries.com/

Not cheap batteryies but the advantages and the expected life cycle I think makes them worth it.

Craig.

[BenBaron]

Ok, found the drain and its definatly the alternator, when connected in the fasion that charges the battery (>14V when running) there is current being drawn with no ignition.

So Im thinking the alternator is a bit dodgy, but I dont really have time before the SVA to swap it out. Whats peoples thoughts on re-charging my battery to full monty, and only connecting it up in the morning of the SVA? Do you think it will last the time? I hope it will but the only other alternative is to disconenct the alternator completly and hope the battery holds out, but again whats peoples suggestions?

cheers
Ben

[craggle]

It may be discharging while the engine is not running but does it still charge when the engine is running. Try a voltmeter on the battery with the engine running and hopefully you will have 14.4ish volts. If you do it should be fine for the day as the SVA is done with the engine running most of the time anyway.
I fitted a large battery cutoff switch with a removable key in the boot next to the battery. Every time I leave the car I remove the key mainly for sucurity reasons but it also protects against unwanted battery drain.

Craig.